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Discussion Starter · #1 · (Edited)
I have a 1995 9000, the coolant never seemed to get into operating temperature. This past winter when I needed the heater working, I flushed the radiator and changed the thermostat. A couple days later my car stared misfiring and I took it to an (unreliable) saab shop here in my town, it sat there a few months and I found out that they never actually touched it for fear of it being a bigger problem. (like a cracked head)

I brought it back here to my house unplugged my injectors one at a time while engine ran and found that # 4 did not change one bit plugged in or unplugged. Then I pulled my ignition module out and put in a spark plug, I would get spark on all except for #4. Then I bought and put a new ignition module in and it is still the same, #4 doesn't fire.
I figure that maybe when I changed the thermostat I may have got something wet with antifreeze that I shouldn't have???
So is there any wiring schematics on here or out there to show me what is before the ignition module and which color wire actually goes to the #4 spark plug coil on the ignition module plug, just in case a wire was eaten by a mouse, simply corroded somewhere or maybe this new module is at fault also?
 

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Any spilled antifreeze will have dried up long ago.

I suspect if any wiring to the DI is damaged it won't work at all.

Check all four injectors have electrical connectors firmly attached.

Put in a set of fresh plugs.

Check the compression of all four cylinders. If you know how do both wet and dry compression.

My guess is head gasket failure.
 

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Discussion Starter · #3 ·
Any spilled antifreeze will have dried up long ago.

I suspect if any wiring to the DI is damaged it won't work at all.

Check all four injectors have electrical connectors firmly attached.

Put in a set of fresh plugs.

Check the compression of all four cylinders. If you know how do both wet and dry compression.

My guess is head gasket failure.
I don't know, head gasket failure doesn't make much sense with one spark plug not firing though? I did isolate the module to the top of the engine to make sure the module was at fault? This car didn't see any real heat either, well not that I know of ?

I used to have a porsche 924 that had a head gasket go. Back then it was my first guess, that it was just a bad plug or timing belt issue. The reason the car blew the gasket was the person who had it before me timed it to the wrong side of tdc.
 

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Discussion Starter · #4 ·
done all that...

I don't know, head gasket failure doesn't make much sense with one spark plug not firing at all? I did isolate the module to the top of the engine to make sure the module was at fault? This car didn't see any real heat either even after the thermostat change, well no heat that I know of ?

I used to have a porsche 924 that had a head gasket go on me after I bought it. Back then it was my first guess that it was just a bad spark plug or maybe timing belt issue. The reason the car blew the gasket was the person who had it before me had it timed to the wrong side of tdc.
 

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Discussion Starter · #6 · (Edited)
That helps me out a lot I do have some bluish corrosion there on the plug and will probably change out the plug on the module, thank you.
never actually worked on Saabs that much, my father had a few of 900's when I was growing up, lots of repair issues also.
The only thing that I notice on these cars is that most of wires seem quite small in gauge as compared to other cars and I hear that there are a lot of grounding wire problems also?
 

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Compared to other cars I've seen, the wires don't seem unusually thin. I haven't had ground problems, but I can see why they might exist. The wires are crimped into their ring connectors. Soldering would be an improvement.
 

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If you find one spark plug that is wet or carbon encrusted, the coil pack (integral with the DIC) that corresponds to it is probably bad - or it could be the primary side of the ignition wiring. The plug gaps are automatically cleaned at each engine shutdown. So if the plug is fouled, it is not firing correctly:

Burn-Off
After the ignition switch has been turned off and the engine has stopped, the main relay remains activated for a further 6 seconds. The Trionic ECM then grounds all the trigger leads 210 times per second for 5 seconds. Each electrode gap is thus cleaned of impurities with more than 1000 sparks.


Too bad you don't have a spare DIC to troubleshoot with. If you pop in a known good DIC and the engine begins to run well...the problem is within the DIC - a coil pack.

If that same test DIC - one that is known good - does not improve the performance of your car, the problem might be in the primary ignition wiring. Here is an image showing where primary ignition wires frequently fail:




One other weak spot you can check without a spare DIC. It's on the secondary (high voltage) side of the ignition - the spring that connects the coil to the spark plug. Check this way:




To Remove


  1. Unplug the ignition discharge module's 10-pin connector.
  2. Remove the 4 bolts.
  3. Lift up the ignition discharge module.
  4. Turn the ignition discharge module upside down and remove the 8 screws.
  5. Lift off the black bottom part of the ignition discharge module.
  6. To change the spring, use a screwdriver to prise out the old spring.
To Fit

  1. Fit a new spring in place.
  2. Fit in reverse order.
Tightening torque, ignition discharge module bolts (4): 11 Nm (8 ft lbs)

You don't need new springs, just stretch the springs out. Also use some emery to clean up the contact points at the top and bottom.
 
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